It would be great if I was shown things "relevant to my interests". That's not what targeted ads are because ad placement depends on who is willing to pay the most, not on what optimally matches what I want. The most obvious example is search ads in the App Store that show you a competitor's product (or an outright scam) as an ad when searching for a specific app. Now extend that kind of dynamic to any other product category and you start to see the problem.